A pitch blade mechanism in a wind turbine acts on the blades of a wind turbine rotor for changing their respective angles to achieve the maximum power. For this reason, blades are pivotally guided about an axis by bearings. Thus, the pitch blade mechanism requires the provision of a seal to prevent lubricant from leaking out and to prevent dust, water, and other contaminants from entering the pitch blade mechanism. The wind turbine pitch blade mechanism is usually provided with an outer seal and an inner seal.
A sealing for this purpose is described in DE 10309383 that shows a pitch mechanism having roller bearings for each blade root. The interface between the blade root and the bearing within the hub is surrounded by a protective shell ring made of a non-corroding material, and the interface between the shell and the adjoining components is protected by an overlapping elastic shell seal.
Wind turbine bearings are generally designed for twenty years of lifetime. Seals that retain grease inside the bearing and protect it from different weather and contamination conditions, however, are not designed for such a lifetime. Therefore, such seals should be replaced with new ones periodically due to wear, dust, etc. Exact seal lifetime is not easily determined as it depends mainly on weather and contamination conditions, but as a reference, seals may be replaced every three years.
Disassembling of an old seal from the wind turbine pitch bearing in situ or during pitch bearing manufacturing is currently very easy and quick as a seal is only needed to be pulled out from a bearing groove or seat.
However, assembling a new seal into a wind turbine pitch bearing mechanism in situ (for example, when it is necessary for a seal to be replaced) or during pitch bearing manufacturing is currently a very difficult and slow operation. Such an in situ operation on a wind turbine usually involves an operator working at a height of over 70 meters from the ground, this being a risky working condition, and taking into account that operations have to be performed outside the hub and around 360° of the blade root.
One method for facilitating the operator insertion of the seal into the bearing groove or seat of a wind turbine pitch bearing mechanism uses manually operated tools. However, they are time consuming and capital intensive because of high technical labor costs involved. Time required for the assembling of a new seal using manually operated tools involves undesirably long downtimes in which no electricity is produced by the wind turbine.
Still a further disadvantage in known seal assembling operations in wind turbines is that they require a lot of free space inside the wind turbine (i.e., the deflector) so that the operator may freely move. This is an especially significant issue when an outer seal is to be fitted into the seat of a wind turbine pitch bearing mechanism. This means that larger deflectors need to be made so that the operator can work comfortably, thus involving higher costs.
Japanese Patent No. JP2003240124 shows a device for disassembling an old seal from a pitch bearing either in situ on a wind turbine or during pitch bearing manufacturing. However, it does not teach about seal assembling operations.
French Patent No. FR2572123 discloses a device for assembling joints on windows or the like in which the seal is directly fixed into a groove of a crossbar or strut by means of jacks and a small wheel pushing the seal into the groove. Two driving rollers are provided to move the wood forward along the machine. This device is only applicable to elements made out of wood, aluminum, or certain joinery elements made out of plastics.